INTRODUCTION The functional textiles have been researched and developed strongly in recent years, contributing to the growth of many industrial fields and the social economic development all over the world. The application of microcapsules is now one of the modern technologies to manufacture the functional textiles, as shown in a lot of researches and commercial products. Microcapsules are tiny particles having size of from one to few hundred micrometers, containing active ingredients packaged within the cores surrounded by the polymer shells. The main advantages of microcapsules are controlling the release of the active ingredient and protecting the active ingredient from the surrounding environment. Therefore, microcapsules have been applied in many textile fields such as thermo-regulating textiles, flame-retardant textiles, cosmetic textiles, fragrant textiles and medical textiles. In the field of medical textiles, by using microcapsules, many kinds of medical ingredients have been incorporated into textiles, including the anti-inflammatory agents such as ibuprofen, dexamethasone and some herbs. Using eco-friendly products is a global trend nowadays, so the application of microcapsules in textile also needs to integrate with this development. The use of microcapsules made from eco-friendly materials for medical textiles has been mentioned in many researches with many kinds of natural active ingredients have been encapsulated in the bio-sourced polymers. However, aside from the polymers and the active ingredients, the surfactants and the solvents are also two essential components of the microencapsulation, but the effort to reduce their hazard has not been in concern in the field of textile. Meanwhile, the natural surfactant quillaja saponin has been approved for human health and been applied commonly in producing emulsions for food, pharmaceutical and cosmetic industry. Besides, in recent years, there have been some studies using less toxic non-halogenated solvent ethyl aceate to replace toxic halogenated sovents in microencapsulation by sovent evaporation method. Beside the microcapsules, the textile substrate is also an important component of the microcapsule-treated fabric. The fabric structure has strong influence on the microcapsule loading capability and the microcapsule distribution on the fabric, and consequently affects the active release capability of the fabric. Due to many advantages such as the softness, the high elasticity, the ability of not curling at edges and the difficulty of unraveling, the interlock knitted fabric is very suitable for the substrate in the medical textiles using microcapsules, especially in compressive bandages. However so far in the knitting field in general and on the interlock fabric in specific, there have been very few researches about the influence of fabric structural parameters on the characteristics of the microcapsule-treated fabrics. It was reported that the loop length obviously affected the microcapsule loading capability of the fabric, but the scientific nature of the influence was not discussed. Moreover, up to now, there have not been any studies about the influence of other structural parameters yet.
TABLE OF CONTENT LIST OF ABBREVIATIONS LIST OF FIGURES LIST OF TABLES 10 INTRODUCTION 12 Chapter 1: Literature review 16 1.1 Microcapsules and their textile applications 16 1.1.1 Microcapsules 16 1.1.2 Applications and requirements of microcapsules in the textile field 20 1.1.3 Microcapsules prepared from environment-friendly materials for textile applications 24 1.2 Microencapsulation by the solvent evaporation technique 25 1.2.1 Techniques of microencapsulation 25 1.2.2 Microencapsulation by the solvent evaporation technique 26 1.2.2.1 Basic principle of the technique 26 1.2.2.2 Important parameters of the microencapsulation by the solvent evaporation technique 27 1.2.2.3 Using non-halogenated solvents in the microencapsulation by the solvent evaporation technique 31 1.2.2.4 The quillaja saponin bio-sourced surfactant 32 1.3 The textile substrates 38 1.3.1 Influence of the textile substrate on the microcapsule loading capability of microcapsule-treated fabrics 38 1.3.2 Influence of the textile substrate on the microcapsule distribution of microcapsuletreated fabrics 40 1.3.3 Influence of the textile substrate on the active release capability from the microcapsule-treated fabrics 41 1.3.4 The interlock knitted fabrics 42 1.4 Textile finishing with microcapsules 45 1.4.1 Techniques of finishing textiles with microcapsules 45 1.4.2 Influence of the drying conditions on the microcapsule morphology after finishing process 47 1.5 Conclusions of the literature review 49 Chapter 2: Experimental methods 50 2.1 Materials 50 2.1.1 Interlock knitted fabrics 50 2.1.2 Chemicals for microencapsulation 51 2.2 Research contents 53 2.3 Experimental techniques 54 2.3.1 Determining the suitable microcapsule size for textile application 54 2.3.2 Evaluating the surface-active properties of quillaja saponin 54 2.3.3 Investigating the influence of the microencapsulation parameters on microcapsule characteristics 56 2.3.3.1 Microencapsulation 56 2.3.3.2 Microcapsule characterization 58 2.3.4 Investigating the influence of textile substrate on the characteristics of microcapsuletreated fabric 61 2.3.4.1 Structural parameters of the interlock knitted fabrics 61 2.3.4.2 Influence of textile material on characteristics of microcapsule-treated fabric 63 2.3.4.3 Influence of the loop length on the characteristics of the microcapsule-treated fabric 67 2.3.4.4 Influence of the fabric extension on the transdermal drug release capability of fabric 72 2.3.5 Investigating the influences of the drying conditions on the microcapsule morphology after finishing process 74 Chapter 3: Results and discussions 75 3.1 Microencapsulation of ibuprofen 75 3.1.1 Determination of the microcapsule size for the targeted textile application 75 3.1.2 Surface-active properties of quillaja saponin S4521 (Sigma Aldrich) 77 3.1.3 Influence of the microencapsulation parameters on the microcapsule size and morphology 79 3.1.3.1 Influence of the saponin concentration 79 3.1.3.2 Influence of the stirring rate 84 3.1.3.3 Influence of the volume of ethyl acetate added to the aqueous phase 86 3.1.4 Conclusions on the microencapsulation parameters suitable for textile applications 90 3.1.5 Other characteristics of C0.075 microcapsules 91 3.2 Influences of the drying conditions on the microcapsule morphology after textile finishing process 93 3.2.1 Influence of the relative humidity during the drying process 94 3.2.2 Influence of the drying temperature 95 3.3 Influence of the textile substrate on the characteristics of the microcapsule-treated fabrics 97 3.3.1 Influence of the textile material type 97 3.3.1.1 Influence on the microcapsule loading capability 97 3.3.1.2 Influence on the microcapsule distribution 99 3.3.1.3 Influence on the ibuprofen release capability of the microcapsule-treated fabric 102 3.3.1.4 Conclusion 104 3.3.2 Influence of the loop length 104 3.3.2.1 Influence on the microcapsule loading capability 105 3.3.2.2 Influence on the microcapsule distribution 114 3.3.2.3 Influence on the ibuprofen release capability of the fabric 126 3.3.2.4 Conclusion 127 3.3.3 Influence of the fabric extension .128 3.4 Conclusion of Chapter 130 Final conclusions and future outlook 134 4.1 Final conclusions 134 4.2 Future outlook 135 REFERENCES 136 LIST OF PUBLISHED WORKS OF THE DISSERTATION 147 LIST OF ABBREVIATIONS Abbreviation Explanation Organizations HUST Hanoi University of Science and Technology IMP Ingénierie des Matériaux Polymères, UMR CNRS 5223 UCBL University Claude Bernard Lyon ASTM American Society for Testing and Materials ISO International Organization for Standardization TCVN Vietnam National Standards Experimental techniques and equipment FRSE Microencapsulation by the solvent evaporation method with the fast rate of the solvent evaporation NRSE Microencapsulation by the solvent evaporation method with the normal rate of the solvent evaporation FTIR Fourier-Transform Infrared Spectroscopy HPLC High-performance liquid chromatography SEM Scanning electron microscopy UV-Vis UV visible spectroscopy Materials and their characteristics CMC Critical micelle concentration E Microencapsulation efficiency Eudragit RSPO Poly(ethyl acrylate-co-methyl methacrylate-cotrimethylammonioethyl methacrylate chloride) 1:2:0.1 HLB Hydrophilic-lipophilic balance MLC Microcapsule loading capability of the microcapsule-treated fabric L Drug loading ratio of microcapsule PCL Poly-ε-caprolactone PCM Phase change material PLGA Poly(lactic-co-glycolic acid) PLLA Poly (l-lactic acid) PU Polyurethane PVA Poly (vinyl alcohol) γ Surface tension of a solution Structural parameters of the interlock knitted fabric l loop length Lu Length of yarn in a structural knitted cell Pd Course density Pn Wale density Ps Area density SKC Structural knitted cell Su Number of the structural knitted cells per unit area of the fabric Mfbr Mass per unit area of the fabric t Fabric thickness D Yarn diameter in the fabric P Fabric porosity ρ Fiber density LIST OF FIGURES Figure 1.1: Microcapsule classification on the basis of their morphology [31] 16 Figure 1.2: SEM image of PLGA microsphere containing progesterone [121] 17 Figure 1.3: An example of the size distribution curve of microcapsules [140] 18 Figure 1.4: Four types of theoretical curves describing the release mechanisms of the active ingredients from the non-erodible microcapsules [104] 19 Figure 1.5: Classification of microencapsulation methods 25 Figure 1.6: Diagram of basic principle of microencapsulation by solvent evaporation technique [76] 26 Figure 1.7: SEM images of microcapsules with different mass ratio of core/shell: 60:40 (A); 70:30 (B); 75:25 (C) [84] 29 Figure 1.8: SEM images of microspheres made by FRSE (on the left) and NRSE (on the right) [26] 31 Figure 1.9: Schematic illustration of a surfactant [49] 34 Figure 1.10: Determination of CMC by the curve surface tension-lnC [92] 35 Figure 1.11: Illustration of a spherical micelle [93] 36 Figure 1.12: General molecular structure of quillaja saponin, in which R1, R2, R3 groups depend on different molecules in the bark extract [98] 37 Figure 1.13: SEM images of fabrics padded with microcapsules: polyester fabric (A) and cotton fabric (B) [125] 40 Figure 1.14: SEM images of polyester fabric (A) and cotton fabric (B) coated with microcapsules containing flame - retardant agent [40] 41 Figure 1.15: Structure (A) and notation (B) of interlock knitted fabric [1] 42 Figure 1.16: Structure of knitted loop [1] 43 Figure 1.17: Model of interlock knitted loop by Dabiryan-Jeddi [27] (A) Front view; (B) Plane view; (C) Side view; (D) a plain structure 44 Figure 1.18: SEM images of wet-coated nylon fabrics with and without microcapsules: without microcapsules (a), with 10% (b), 20% (c) and 30% microcapsules (d) [66] 47 Figure 1.19: SEM images of dry-coated nylon fabrics with and without microcapsules: without microcapsules (a), with 10% (b), 20% (c) and 30% microcapsules (d) [66] 47 Figure 1.20: SEM images of microcapsule padded cotton fabrics with different drying temperature 120 o(11.1-11.2); 140 oC (11.3-11.4); 160 oC (11.5-11.6) [88] 48 Figure 2.1: Structural formula of ibuprofen (C13H18O2) [14] 51 Figure 2.2: Chemical structure of Miglyol 812 [58] 52 Figure 2.3: Chemical structure of eudragit RSPO [147] 53 Figure 2.4: Tensiometer SEO-DST30M (Surface & Electro-Optics) 55 Figure 2.5: Diagram of microencapsulation of eudragit RSPO loading ibuprofen by solvent evaporation method 56 Figure 2.6: Equipment system for microencapsulation 57 Figure 2.7: Centrifuge G-16KS of Sigma 57 Figure 2.8: Optical microscopy Olympus EX 41 58 Figure 2.9: Scanning electron microscopy QUANTA FEG 250 58 Figure 2.10: Mastersizer 2000, Malvern Instruments 59 Figure 2.11: Ultrasonic equipment Fisher biolock Scientific 750W 60 Figure 2.12: Spectrometer UV-Vis Lamda 35 (Perkin Elmer) 60 Figure 2.13: Gas chromatograph Agilent Technology 6890N 61 Figure 2.14: Experimental washing machine Electrolux 62 Figure 2.15: Laboratory conditioning chamber M250-RH 62 Figure 2.16: Electronic scale OHAUS - PA413 63 Figure 2.17: Thickness gauge 63 Figure 2.18: Vacuum drier France Etuves 63 Figure 2.19: Fabric samples soaking in the microcapsule suspension 64 Figure 2.20: Scanning electron microscopy QUANTA FEG 250 – FEI company 65 Figure 2.21: Interface of Meander 3.1.2 during determining the area of microcapsule aggregate 65 Figure 2.22: Glass jar simulating Franz diffusion cell 66 Figure 2.23: Drug release in vitro experiment 66 Figure 2.24: HPLC system of SHIMADZU 67 Figure 2.25: Coating equipment Mini Coater (DaeLim Starlet Co.,Ltd) 68 Figure 2.26: Vacuum drier OV-11 68 Figure 2.27: Scanning electron microscopy JEOL JSM - 7600F 70 Figure 2.28: A step in the in vitro experiment of transdermal drug release 71 Figure 2.29: HPLC system of Merck Hitachi 72 Figure 2.30: Experimental design to create different levels of fabric extension 73 Figure 3.1: SEM image of the surface of fabric B3 75 Figure 3.2: Distance between fibers in the region of loop legs on cotton interlock fabric B3 76 Figure 3.3: Distance between fibers in the region created by overlapping loops on cotton interlock fabric B3 76 Figure 3.4: Surface tension of aqueous saponin solutions according to saponin concentration 78 Figure 3.5: Size distributions of microcapsule lots C0.025, C0.050, C0.075 and C0.100 80 Figure 3.6: Adense/Asurf ratio depending on the saponin concentration 81 Figure 3.7: Optical microscope images of microcapsules C0.025 (A), C0.050 (B), C0.075 (C) and C0.100 (D) 83 Figure 3.8: Optical microscope images of microcapsules R700 (A), R650 (B) and R600 (C) 85 Figure 3.9: Size distributions of microcapsules R700, R650 and R600 86 Figure 3.10: Size distributions of microcapsule lots S0, S8 and S12 87 Figure 3.11: Optical microscope image of microcapsule S8 88 Figure 3.12: Optical microscope images of the cotton interlock fabrics coated with microcapsules S0 (A), S8 (B) and S12 (C) after 24 hours of vacuum drying at 25oC 90 Figure 3.13: SEM images of the C0.075 microcapsules (A): overall image; (B): image of the microcapsule surface 92 Figure 3.14: SEM image of cross-section of microcapsule C0.075 92 Figure 3.15: SEM image of the microcapsule-coated fabric dried at 25oC with the relative humidity of 65% 94 Figure 3.16: SEM image of the microcapsule-coated fabric dried at 25oC with the relative humidity of 20% 94 Figure 3.17: SEM image of the microcapsule-coated fabric dried at 25oC with relative humidity of 0% 95 Figure 3.18: SEM image of the microcapsule-coated fabric vacuum dried at 25oC 96 Figure 3.19: SEM image of the microcapsule-coated fabric vacuum dried at 35oC 96 Figure 3.20: SEM image of the microcapsule-coated fabric vacuum dried at 45oC 96 Figure 3.21: SEM image of the microcapsule-coated fabric vacuum dried at 60oC 96 Figure 3.22: SEM images of the microcapsule-treated fabrics Cot_1 (A), 6535_1 (B) and Pet_1 (C) 101 Figure 3.23: Chemical structure of polyester fiber 102 Figure 3.24: Chemical structure of cellulose (main component of cotton fiber) 102 Figure 3.25: Release rate of ibuprofen from microcapsule-treated fabrics according to the type of the textile material 103 Figure 3.26: Microcapsule loading capability of the fabrics according to the loop length with a microcapsule concentration of 14 mg/ml 107 Figure 3.27: Microcapsule loading capability of the fabrics according to the loop length with a microcapsule concentration of 24 mg/ml 108 Figure 3.28: Fabric density according to the loop length 111 Figure 3.29: Fabric porosity according to the loop length 112 Figure 3.30: SEM images of the lower surface of the fabrics B1 (A) and B5 (B) 113 Figure 3.31: SEM images of the fabrics after microcapsule application by the coating technique B1 (A), B2 (B), B3 (C), B4 (D) and B5 (E) 117 Figure 3.32: SEM images of the fabrics after microcapsule application by the impregnating technique: B3 (A), B4 (B) and B5 (C) 125 Figure 3.33: Weight percentage of ibuprofen released into the receptor fluid according to the fabric extension 129 LIST OF TABLES Table 1.1: The values of K for different kinds of fabrics [17] 42 Table 2.1: Information of chemicals used for microencapsulation 51 Table 2.2: Some properties of ibuprofen [151] 51 Table 2.3: Doses of ibuprofen for adults and children [14, 65] 52 Table 3.1: Surface tensions of saponin solutions in distilled water according to the concentration 77 Table 3.2: d(0.5) diameter and span values of microcapsule lots C0.025, C0.050, C0.075 and C0.100 79 Table 3.3: d(0.5) diameter and span values of microcapsule lots R700, R650 and R600 85 Table 3.4: d(0.5) diameter and span values of microcapsule lots S0, S8 and S12 87 Table 3.5: Structural parameters of the interlock knitted fabrics used to investigate the influence of the textile material type on the characteristics of the microcapsule-treated fabric 97 Table 3.6: Microcapsule loading capability of the fabrics knitted from different materials 98 Table 3.7: Results of two independent samples t tests for fabrics knitted from different materials 99 Table 3.8: Statistical results of the area of microcapsule aggregates on different kinds of fabrics 101 Table 3.9: Ibuprofen release rate from the microcapsule-treated fabrics having different textile materials 103 Table 3.10: Microcapsule loading capability of the fabrics according to the loop length with a microcapsule concentration of 14 mg/ml 105 Table 3.11: Microcapsule loading capability of the fabrics according to the loop length with a microcapsule concentration of 24 mg/ml 106 Table 3.12: Results of the t tests according to the loop length with a microcapsule concentration of 14 mg/ml 106 Table 3.13: Results of the t tests according to the loop length with a microcapsule concentration of 24 mg/ml 107 Table 3.14: Practical structural parameters of the fabrics according to the loop length 109 Table 3.15: Microcapsule loading capability of the fabrics according to the loop length with a microcapsule concentration of 20 mg/ml 113 Table 3.16: Results of the t tests according to the loop length with a microcapsule concentration of 20 mg/ml 114 10 ... microscopy UV-Vis UV visible spectroscopy Materials and their characteristics CMC Critical micelle concentration E Microencapsulation efficiency Eudragit RSPO Poly(ethyl acrylate-co-methyl methacrylate-cotrimethylammonioethyl... ratio of microcapsule PCL Poly-ε-caprolactone PCM Phase change material PLGA Poly(lactic-co-glycolic acid) PLLA Poly (l-lactic acid) PU Polyurethane PVA Poly (vinyl alcohol) γ Surface tension... ABBREVIATIONS Abbreviation Explanation Organizations HUST Hanoi University of Science and Technology IMP Ingénierie des Matériaux Polymères, UMR CNRS 5223 UCBL University Claude Bernard Lyon ASTM